In longwall mining systems roof supporting structures such as chocks and shields are widely used. Face haulage is accomplished with chock-positioned floor-supported conveyors. Typically, armoured drag face conveyors are positioned by frames which extend forwardly on the mine floor from the chocks. Coal dislodged from the face, by either plow or shearer, falls onto the drag conveyor and is transported to secondary mine haulage. When the coal has been removed for a certain distance down the panel the first chocks which have been passed are advanced toward the rib of the panel. At the completion of the cut all the chocks will have been moved and are normally maintained in a straight line. As the chocks advance, they also advance the conveyor which has some flexibility and is bent in a gradual curve permitting this forward movement. This system is inadequate because limited flexibility of the conveyor restricts immediate large movements of the chocks subsequent to the passage of the mining device. Furthermore, to move the conveyor to a new mining area in the mine as a result of either completing the mining in an area or due to encountered severe geological conditions, requires that the entire conveyor be disassembled, moved, and re-assembled requiring a considerable amount of time and effort.
In addition to this lack of maneuverability of the face haulage system, the longwall system is also characterized by poor respirable dust control. This is because the mining machine, plow or shearer which typically removes a 30 inch slice of coal for each pass, is operated in both directions along the face. Ventilation is unidirectional. Therefore, during the mining cycle dust is passed away from the mining machine when it is moving in one direction and over the mining machine when it returns.
Shortwall mining takes advantage of the excellent roof supporting features of the longwall system and uses the highly adaptable and flexible continuous mining machine developed for room-and-pillar mining. The continuous miner operates under the chock system which provides roof support. Because the mining cycle is unidirectional, the mining machine taking an 8-10 foot cut, the ventilation system which is also unidirectional blows all dust and methane away from the working area. Typically the face haulage system for shortwall mining utilizes shuttle cars. A car will move in under the chocks behind the continuous miner, be loaded with coal by the mining machine, back out, and transport the coal to secondary haulage. A second shuttle car then moves in under the chocks behind the continuous miner for loading. Because of the delays which result from one loaded shuttle car moving out from behind the continuous miner and the empty shuttle car moving into position, the length of the wall had to be shortened. Thus, the so-called shortwall system.
A comparable chock system is disclosed in Allen et al (supra). This system has advantages in that the roof support, mining and trnsportation are coordinated so that productivity is increased and safety enhanced. However, it has certain disadvantages in that the conveyor's supports must be withdrawn and re-installed behind the continuous miner each time a new cut through the panel is made.
Recently, Joy Manufacturing Company has disclosed a chock system which is used in conjunction with a continuous miner and which partakes of characteristics of both long and shortwall mining. After entries have been developed in a room-and-pillar manner so as to leave a panel there between, and roof bolts have been implaced, chocks are installed in the entry adjacent to the mining panel. Then the mining machine starts a cut through the panel and, as the machine advances along the cut, the roof support chocks move in, one by one, along the row behind it, a ground supported flexible conveyor train advances along behind the continuous miner beneath the chock arms. This system is not useful because of problems of maneuvering, belt carryover, and materials for construction particularly associated with the belt flexibility.
The Lee-Norse Company and the Long-Airdox Company have also attempted to overcome the face haulage dilemma for shortwall mining through the use of their respective extensible belt systems. However, problems resulting from the inability to adequately maneuver around corners also makes these systems unsatisfactory.
The objective now is to provide a new system wherein developed and commercially available face haulage equipment can be used with the advantageous features of both the longwall and shortwall systems and provide features which are not available in any system. That is, the roof support and long operating face features of the longwall system, and the highly mobile and flexible mining machine, the continuous miner, and the unidirectional ventilation scheme from the shortwall system, will be utilized by providing an articulated support system which is attached to the chocks of the roof support system. The articulated support system allows ancillary systems to be moved in a continuous manner into and out of the working face.
The primary objective of the invention is to provide an ancillary support system which is articulated in such a manner that as the individual roof support members, chocks, are advanced behind a mining machine, each one carries forward a segment of the ancillary support system which, when linked together, form the whole ancillary support system. As used hereinafter and in the appended claims, the term chock or chocks shall mean chocks, shields, or other related mechanical devices for roof support. The term mining machine shall refer to continuous miner, header, borer, auger, cutter, shearer, plow or other related commercial mechanical devices used to obtain minerals from the earth's crust. It is further noted that for the purpose of this specification and the appended claims that the term conveyor systems is not limited to the preferred embodiment, the flexible frame endless conveyor. It will be apparent to those skilled in the art that the ancillary support system is readily adaptable to support other conveyance systems such as multiple-unit cascading trains, flexible conveyor trains, hydraulic tube transport, pneumatic tube transport, etc.
The ancillary support system of the subject invention provides a mechanism wherein individual monorail sections are used to form a continuous overhead monorail that is used to support a flexible frame endless conveyor that therein provides continuous face haulage for the mining system. To support the flexible frame endless conveyor, individual monorail sections are suspended from the roof beams on the forward side of the chocks. As the chocks are moved in behind the continuous miner, each of the monorail sections is moved into place and connected onto the last previously moved-in one so as to extend the monorail terminus forwardly as the continuous miner advances. According to one embodiment of the invention, the monorail ancillary support system sections are mounted only on forward sides of the chocks. According to another embodiment, similar monorail ancillary support system sections on the rear side of the chocks are used for supporting a second flexible frame conveyor. The first conveyor running along the forward side of the chocks conveying the mineral away from the mining machine. The second conveyor on a retreating trackway on the rear side of the chocks conveying backfill material into the subsidence area of the mine.